Multi-value Dimensions

The preceding examples have dealt with single-valued dimensions; where more than two Dimension Points are involved, the Dimension is said to be multi-valued. Two classes of multi-valued Dimensions exist, namely chained and parallel. The example illustrates a a chained Dimension.

Such a dimension (which is still represented by a single LDIM element) is created by repeating the DIMTO part of the DIMFROM . . . DIMTO command line, moving the cursor crosshairs to each Dimension Point in turn. Before/After Linear Dimensions can be created by a command sequence, for example:

NEW LDIM

DIMFR ID @ DIMTO ID @ DIMTO ID @

An additional ‘link’ can be inserted in or added to a chained Dimension (or a single-valued Dimension can be ‘converted’ to a chained Dimension) through use of the INSERT command.

INSERT ID @

and using the cursor to nominate the link element. P-points, p-lines, dimension points or 3D points can also be used as links using:

INSE IDP @

INSE IDPL @

INSE IDPD @ or

INSE POS @

A Dimension Point can be constructed using Draw’s point construction facilities. Refer to Point and Line Construction for further information. For example:

INSE POS OF @

INSE POS OF ENDP OF @

Other constructions, for example, INTERSECTION and MIDPOINT can be used. The facility (which is only valid in a plan or elevation View) enables Dimension Points to be positioned on any line of the Design graphics. The constructed Dimension Point has a 3D position (for example, it is a DPOI) but is not associated with the identified Design element.

The effect of the INSERT command is to create a new Dimension Point of the appropriate type at the last position in the owning LDIM's member list. INSERT can be used at Dimension Point or LDIM level.

Dimensions are drawn in the same order as the LDIM’s member list order. If the elements get out of the correct order then the display of the Dimension becomes confused. The situation can be corrected by the SORT DIMENSIONPOINTS command (minimum abbreviation SORT DIM), which can be used at Dimension or Dimension Point level. The example illustrates the effect of the command.

The example illustrates a parallel Dimension.

A parallel Dimension can be produced by setting the LCHA attribute of an LDIM as appropriate: